Rains clear up Manchhar Lake but not enough, says expert

Levels of harmful chemicals have been partly diluted.

HYDERABAD: The harmful level of total dissolved solids (TDS) in Manchhar Lake has gone down by one-fourth but are still not within the World Health Organisation’s permissible limits.

According to water expert Dr Ahsan Siddiqui, the TDS has reduced to about 1,200 levels in different parts of the lake from about 5,000 before the monsoon rainfall. “The reason to be happy is not that the WHO standard is closer but that people are exposed to less health hazards,” said Siddiqui while addressing a press conference on Thursday.

Siddiqui, a private expert and visiting faculty in five national and foreign universities, has been monitoring the lake and managing its discharge into the Indus River for the last several years. He was ordered to do this by the Sindh High Court after 60 people were killed after drinking the lake’s poisonous water in Dadu, Jamshoro and Hyderabad in 2004. TDS is a measure of organic and inorganic substances in water. Its primary source is the agricultural and industrial run-off as far as the lake is concerned. It contains chemicals such as phosphate, sodium, potassium, calcium, nitrates, chloride and more harmful elements like pesticides and industrial effluents.

Manchhar, the largest freshwater lake in Pakistan and one of the biggest in Asia, is located in Dadu district. Spread over 200 square kilometres, it is inhabited by up to 20,000 fishermen who live inside it and hundreds of thousands people in the surrounding areas who also drink from the lake. It is filled by water streaming from the mountains of the Khirthar range after it rains, the Indus river and the poisonous Main Nara Valley drain.

It is the drain which is the sole source of the lake’s pollution. With a 1,000-cusesc capacity, the drain brings saline water and industrial effluents from northern Sindh to the lake. “The drain is like a sword of Damocles dangling over the head of Sindh’s people,” the water expert commented. He lamented that there is no near term solution to this problem.

According to Siddiqui, the drain will again start to pollute the lake after one and a half months. “With a reduction in the drain’s discharge and a reduced level (RL) of the lake, the TDS level will increase.”

Currently, the lake’s RL - a measure of the bed level - is 111.75 RL, 4 RL below the danger level of 116 RL which can cause breaches and flooding. Siddiqui said that between 1,000 cusecs to 4,000 cusecs per day are being released from the lake to the Indus to reduce the level to 106 RL.

Published in The Express Tribune, October 12^th, 2012.